Ok, after having some problems with my gstreamer plugins (none of the
gstreamer were working when trying to play MP3), which BTW led me to
open this bug[1], I seem to have fixed them because now I'm able to
play mp3 with a very lightweight gstreamer player (called christine, I
got it from packman).

However, neither Banshee or Totem work! Totem seems to play it (no
crash, and I see the image effects while the progress bar advances)
but I get no sound. And Banshee refuses to play showing an "X" icon
and just showing: "[Error 12:48:38.277] GStreamer stream error: Failed"

Is this then a Banshee bug? It seems also that the totem problem is a
bug, but maybe related to pulseaudio? I'm using opensuse11.0.